1. Field of the Invention
The present invention relates to fluid flow assemblies and, in particular, to tubular assemblies for the flow of fluid in hydraulic systems More particularly, the present invention relates to a method for determining the robustness of an endform tubular fluid flow assembly having measurable elements inherently formed therein and for predicting the performance of the endform tubular fluid flow assemblies in high pressure applications for prolonged periods of time.
2. Discussion of Related Art
Fluid flow assemblies for power steering systems include a steering gear housing, a steering gear disposed in the steering gear housing, a pump for moving the power steering fluid under pressure, a supply line for transporting pressurized fluid from the pump to the steering gear, and a return line for transporting the fluid from the steering gear back to the pump. Typically, such assemblies include one or more brackets or support members that are used to mount the power steering components within an automotive vehicle. The end of each of the supply line and the return line may be individually connection to an inlet port and an outlet port in the housing, respectively, by employing means such as a “tube-o” connector wherein a threaded nut is used behind each of the tube-o connectors to secure each of the tubes to a corresponding threaded port in the housing. Tube-o connectors are considered to be inefficient since they require a separate installation step for each connection.
Other assemblies have been developed wherein a bracket is used to simultaneously couple a fluid supply line and a fluid return line in a fluid flow assembly using a single fastener wherein the complete assembly is connected to a housing with the torque of the single fastener. While the single torque bracket connection is effective for reducing the number of operational steps necessary in the assembling process, such connections are unsatisfactory because they generally require that at least one of the tubular members be brazed into a machined connector. Brazed connections are not reliable, particularly in applications where the brazed part is subjected to the harsh environmental conditions present in the engine compartment of an automotive vehicle. For example, the brazed part may be subjected to extremely cold temperatures in winter during periods when the automotive vehicle is not operating and then suddenly required to withstand high temperatures during operation of the automotive vehicle. Constant vibrational episodes and occasional debris entering the compartment also severely reduce the life expectancy of such brazed connections. Another disadvantage of prior brazed clamp plate connections is that the clamp plate does not sit flush against the housing, such that when torque is applied to the fastener, the bracket may distort leading to premature o-ring failure.
U.S. Pat. No. 7,032,500 describes a fluid flow assembly for a power steering system wherein both a pressure line assembly and a fluid return line are simultaneously connected to a steering gear using a bracket requiring a single fastener. The bracket includes an aperture through which the high pressure line extends and a notch configured to receive a return line assembly. The return line assembly includes a connector member to which the line is brazed or welded. The connector member also includes a pair of circumferential flanges, which allows the bracket to swing over the connector member such that the hose assembly is secured to the bracket member between the pair of circumferential flanges. In such arrangement, the connector is compressed into the port to create a seal The high pressure tube is deformed to create a first bead and, after the high pressure tube is inserted through the bracket, a second bead is formed to secure the tube to the bracket. Such arrangements are not without disadvantages. For example, such fluid flow assembly may employ undesirable brazing or welding for securing at least one of the supply hose and the return hose to the connector. Also two separate steps are needed to form the two beads on either side of the bracket for securing the non-brazed high pressure line to the bracket. Such arrangement is not only time consuming and labor intensive, but the tube may be susceptible to undesirable axial rotation as well as up/down and side to side movement in the bracket. Such undesirable movement severely limits the life expectancy of the assembly Furthermore, each of the return and pressure hoses require the additional step of forming a groove in the ends of the hoses for receiving an o-ring. Consequentially, current tubular assembly design does not provide an economical fluid flow bundle having assured long term dependability and structural integrity, nor does it provide inherent features, which allow the reliable assessment of the robustness of such fluid flow assemblies.
Therefore, it would be desirable to provide a method of endforming a tubular assembly that would having a robust design exhibiting improved sealability, long term dependability and reduced manufacturing costs, and which would have inherent computable quality control features for assessing the robustness of the endform tubular assembly and for predicting the performance of the endform tubular assembly in high pressure applications for prolonged periods of time.
3. Related Applications
The contents of copending applications U.S. Ser. No. 11/769,305, and U.S. Ser. No. 11/769,316, both relating to the same subject matter as the present application, and both of which are filed simultaneously herewith, are incorporated herein by reference thereto.